Want to build a "cheap" recording booth.

Okay The acoustics in my room.. are great, when im recording drums, guitar and bass, Its not overwelming. Its not too dead. Well I want a dead room/no reverb at all booth to record my vocals in.
How could I go about this without having to build onto my "room" with nails? Could I make say a booth out of plywood? and say Pillows/egg crates/ foam?